I am not new to Subversion, but I have up till now used Tortoise and never the commadn line. My question is, how do I ignore all files like *.o from the ENTIRE source not j
Edit
The original answer provided below was given prior to Subversion v1.8 which introduced a way to set the default repository level ignore (called svn:global-ignores) without overriding/replacing the svn:ignore property on the root directory and every single subdirectory. Since 1.8, the best way to achieve what you would like is to invoke the following command (credit goes to TManhente):
svn propset svn:global-ignores '*.o' .
On earlier versions (and on later versions), you can still use the approach indicated in the original answer below; however, be aware that this assumes that you are okay with replacing/overwriting the svn:ignore property on each and every subdirectory... this may be fine for a smallish/newish repository but is probably not what you want if you have a large/old repository in which some subdirectories may have independent svn:ignore properties that you do not wish to overwrite.
Original answer
You can use the "-R" or "--recursive" option with "svn propset" as in the following command:
svn propset svn:ignore '*.o' . --recursive
More info
For both cases, you can use the following command for more info about svn propset:
svn help propset